How to get out of 2D view
You have entered orthographic mode. Press Numpad 5 to toggle it on and off, or simply hold down the Scroll Wheel and move the mouse you will be out of it. If you want to use orthographic modes in the future:
Numpad 1 = front orthographic
Numpad 3 = side orthographic
Numpad 7 = top orthographic
Numpad 5 = flip (ex: top flips to bottom)